We were debugging an issue yesterday where 'localhost' could not be resolved inside a container in openshift origin v1.3.0-alpha.3. I'm not sure if this is openshift or kubernetes-related, but thought I'd ask here first.

We have two containers running on a pod, and one container is connecting to the other using 'localhost'. This has worked fine for several months, but stopped working yesterday. We resolved the issue by using 127.0.0.1. We were also able to use the pod hostname as well.

I'm thinking this might be related to IPv6, given that /etc/hosts seemed to contain IPv6 records for localhost, and the other container may be listening on IPv4 only. I tried disabling it with sysctl net.ipv6.conf.all.disable_ipv6=1 to verify, but I still saw the same issue.